Tilting boom for pipe laying tractor or other vehicle



1961 N. M. ERDAHL ETAL 2,967,628

TILTING BOOM FOR PIPE LAYING TRACTOR .OR OTHER VEHICLE Filed Oct. 15, 1959 INVENT RS /l//c OLA/ M DAHL ORMA/V 15 lP/Sk y JOHN/{MCCARTHY ATTORNEYS United States Patent TILTING BOOM FOR PIPE LAYING TRACTOR OR OTHER VEHICLE Nicholai M. Erdahl, Milwaukee, Wis., and Norman E. Risk and John H. McCarthy, Peoria, 111., assignors to Caterpillar Tractor Co., Peoria, 111., a corporation of California Filed Oct. 15, 1959, Ser. No. 846,654

4 Claims. (Cl. 214-1) The present invention relates to improvements in tractor mounted booms and particularly to improvements in means for tilting the boom to improve the distribution of weight which effects the balance of the tractor when it is operating on sloping terrain.

In the construction of long cross country pipe lines, it is common practice to join together, usually by welding, many lengths of pipe while they are accessibly positioned on the surface of the ground alongside a ditch in which the pipe is to be laid and covered, and then to deposit a long line of the connected lengths of pipe into the ditch. Depositing of the pipe in the ditch isvaccomplished with a so-called pipelayer which is a tractor having a side mounted boom for supporting the pipe through the medium of a cradle adapted to embrace the pipe and slide longitudinally of it usually with the aid of rollers or other anti-friction means. Since the pipe line generally parallels the terrain of the earth the pipelayer is required to operate on uphill and downhill grades and the cable or fall which supports the cradle seeks a plumb or vertical position, swinging either forwardly or rearwardly of the tractor creating instability and loss of traction.

Efforts to correct this undesirable situation have been made, usually by supporting the boom for tilting movement in a direction fore and aft of the tractor and providing power means for effecting such tilting. Hydraulic jack means have been disposed within either one or both legs of the boom where it is of A-type construction and such jacks have also been proposed for use in other positions adjacent the lower end of the boom. These efforts have proven undesirable because, in one case, the jacks are disposed in a position to support the entire load of the boom and the pipe carried by it and must be of excessive size to accommodate the loads encountered. In both cases the jacks, being disposed adjacent the lower end of the boom, occupy space needed for other purposes and are subject to frequent damage because of interference with the cradle as well as the pipe being handled.

It is the object of the present invention to provide improved means for tilting a tractor mounted boom which overcomes the disadvantages of the proposals referred to above, which enables the use of relatively small jacks so disposed that they are unlikely to become damaged and so arranged that the operation of tilting the boom is accomplished with forces of relatively low magnitude.

Further and more specific objects and advantages of the invention are made apparent in the following specification wherein reference is made to the accompanying drawing illustrating a preferred form of the invention.

In the drawing:

Fig. 1 is a schematic view of a pipelayer tractor with a side boom having tilting means embodying the present invention; and

Fig. 2 is an enlarged schematic view of the same tractor operating on a slope with the boom tilted to accommodate for the inclined position of the tractor and show- Patented Jan. 10, 1961 ICC ing a pipe cradle supported by the fall of the boom with the position of a portion of a pipe line in the cradle indicated in dotted lines.

A tractor is shown in the drawings at 10 as supporting a boom which comprises two vertical legs 11. The legs of the boom are supported by the tractor as on the track frame 12 thereof by universal type hinge connections 13, each of which includes a pintle 14 for permitting the boom to swing outwardly to one side of the tractor and a pintle 15 for permitting the top of the boom to swing longitudinally with respect to the tractor in accordance with the present invention. The upper ends of the boom legs 11 are connected by a link 16 and pivot pins 17 and the link 16 has ends 18 which project forwardly and rearwardly of the legs 11 and serve as supports for a pair of double acting hydraulic jacks 19 pivotally connected between the projecting parts 18 and brackets 20 on the legs of the boom. The link 16 which connects the tops of the legs supports one of a pair of blocks 21 and 22 through which one end of a cable 23 passes to provide a fall which supports a cradle 24. The opposite end of the cable 23 passes through a fair-lead 25 and its opposite end is wound upon and controlled by a winch, not shown, disposed on the opposed side of the tractor 10 for raising and lowering the cradle 24.

Fluid under pressure may be directed to either end of the jacks 19 by means of a conventional fluid circuit and controls therefor, not shown, to adjust the jacks to similar positions, such as illustrated in Fig. 1, where the position of the center line of the boom is normal to the tractor and to level ground upon which it is supported.

When the tractor, as shown in Fig. 2 is operating on an uphill grade, the forwardly disposed jack 19 is extended and the rearwardly disposed jack is contracted to swing the legs 11 of the boom about their supporting pintles 15 forwardly and thus cause the fall of the cable which supports the cradle 24 to seek a vertical or plumb position which is substantially over the center of gravity of the tractor. This is important because as the tractor moves forwardly the cradle 24 does not always advance at a speed which corresponds to that of the tractor but, in spite of anti-friction members represented at 26 thereon which support the pipe line in the position represented in broken lines at 27, friction often retards the movement of the cradle with respect to the pipe. The cradle thus rides behind its normal plumb position until the tractors forward movement is sufficient to overcome the friction and the cradle then moves abruptly or lunges forwardly until the fall of the cable which supports it again attains a substantially plumb position. This occasions a somewhat jerky type of operation with the weight supported by the boom shifting to and away from its preferred position over the center of gravity of the tractor and creates an undesirable tendency for the tractor to lose traction or, in extreme cases, to turn over.

The operation when the tractor is working downwardly of a hill is reversed by reversing the flow of fluid to the jacks 19 and thereby causing the boom to tilt in a rearward rather than a forward direction. Because the extensions 18 of the member 16 which connects the upper ends of the boom legs form lever arms, the force required to tilt the boom is minimized and jacks of relatively small size may be used. The jacks are also conveniently positioned outside of the space included between the legs 11 where they do not interfere with the fall and they are sufliciently high to avoid possibility of their being struck by the cradle or the pipe itself.

While two jacks 19 are disclosed herein, a single jack may be employed to produce the same result eliminating the necessity of one of the projections 18 and one bracket 20. Two jacks may, however, be preferred because'of 3 the distribution of stresses obtained and the possibility of using smaller jacks and lighter linkage.

We claim:

1. In a vehicle mounted boom including two spaced upstanding legs, means to tilt the boom for improving distribution of weight supported thereby when the vehicle is disposed on an incline comprising pivotal connections between the lower ends of the legs and the vehicle, a link extending between and pivoted to the legs adjacent their upper ends, and a double acting power actuated extensible member between said link and one of said legs.

2. In a vehicle mounted boom including two spaced upstanding legs, means to tilt the boom for improving distribution of weight supported thereby when the vehicle is disposed on an incline comprising pivotal connections between the lower ends of the legs and the vehicle, a link extending between and pivoted to the legs adjacent their upper ends, said link having an end projecting beyond its pivotal connection with one leg, and a double acting power actuated extensible means between the outer end of the projecting portion and the adjacent leg.

3. In a vehicle mounted boom including two spaced upstanding legs, means to tilt the boom for improving distribution of weight supported thereby when the vehicle is disposed on an incline comprising pivotal connections between the lower ends of the legs and the vehicle, a link extending between and pivoted to the legs adjacent their upper ends, said link having ends projecting outwardly beyond its pivotal connections with said legs, and power actuated extensible means operatively connected with the outer end of each extension and the outer edge of each leg.

4. In a vehicle mounted boom including two spaced upstanding legs, means to tilt the boom for improving distribution of weight supported thereby when the vehicle is disposed on an incline comprising pivotal connections between the lower ends of the legs and the vehicle, a link extending between and pivoted to the legs adjacent their upper ends, said link having ends projecting outwardly beyond its pivotal connections with said legs, double acting power actuated extensible means operatively connected with the outer end of each extension and a point on each leg below its upper end.

No references cited. 

